In the field of blood treatment, hemodialysis is the most widely used technique, although other techniques are also available such as plasmapheresis, hemoperfusion, blood oxygenation, and techniques for passing blood through blood treatment media such as an absorptive agent for the removal of toxins or the like. Typically, an arterial blood set delivers blood from the patient to the hemodialyzer or other desired blood treatment unit. After the blood has passed through the hemodialyzer, it is conveyed through a venous blood set back to the patient.
The arterial and venous blood sets typically each have about two meters of tubing, extending from patient connectors to other set components such as bubble removal chambers, a length of roller pump tubing or another pump device fitment, branch connection sites, a pressure pillow, and the like. Also, typically another meter of tubing extends between these various other set components and the dialyzer or other blood treatment device. Numerous other known devices may also be positioned on the blood sets, such as filters.
In the early days of dialysis, blood lines and dialyzers were hand-assembled before dialysis, and then disassembled, piece-by-piece, after dialysis for cleaning and resterilization. These early dialyzers were of the plate dialyzer form, and, generally, everything was reused except for the dialyzing membranes. Typically, glass chambers and various metallic fittings were press fit into latex blood tubing, with these components being reused a large number of times.
Since such a process was very expensive in terms of labor cost and time consumption, plastic, presterilized dialyzers and blood lines were introduced in the late 1960's. Initially, these items were disposed of after a single use. However, in due course, the dialyzers particularly began to be reused, always on the same patient and typically for only four to six uses. In countries with less government funding and/or lower cost of labor the reuse of dialyzers, bloodlines, and even fistula needles has been and still is common, despite safety issues.
When U.S. government funding of dialysis began in the mid 1970's, dialyzer reuse substantially disappeared. However, since another funding change in 1982, U.S. dialyzer reuse has been once again increasing.
Particularly, hollow fiber dialyzers have been reused, especially since the introduction of noncellulosic membranes such as polysulphone, which are more capable of exposure to oxidizing agents such as more concentrated liquid bleach, so that at the present time most hemodialyzers are reused, with the reuse typically being done with semi-automated equipment that controls the rinsing, bleach and antiseptic solution application, and other aspects of the disinfection process. Typically, in the more recent reuse techniques, the dialyzer is first disconnected from the arterial and venous blood sets, which are thrown away. Hollow fiber dialyzers have their headers removed in some cases so that the fiber manifolds can be swabbed and cleaned. Then, the dialyzers are connected by short reuse tubes which join its blood inlet, outlet, and dialysate ports to the respective ports on the reuse equipment. The blood and dialysate pathways are sequentially rinsed, followed by application of a bleach solution and another water rinse, following which the dialyzer is filled with a disinfectant solution. The dialyzer is then separated from the short reuse connecting tubes capped, and then stored until the patient's next dialysis. Dialyses are typically performed on a patient three times a week.
Immediately prior to the next use, the dialyzer is typically connected to a new arterial set that has been previously primed with sterile, physiological saline. Then a venous set is attached. The system is rinsed with sterile physiologic saline solution for essential elimination of the disinfectant.
Commonly, blood lines of the arterial and venous sets have not been reused, partly because the cost of blood lines is less than the cost of dialyzers, and also because blood lines are more difficult to reuse than dialyzers. This is because, contrary to the typical hollow fiber dialyzers, traditional blood lines have numerous branch lines, dead end spaces, and enlarged spaces such as are found in the bubble removal chambers and pressure pillows. Thus, efficient, effective cleaning of traditional arterial and venous sets is difficult or impossible.
Also, conventional arterial and venous sets are more difficult to set up for dialysis reuse than typical hollow fiber dialyzers, since the above mentioned components also cause difficulties in the removal of the chemical sterilant prior to reuse. The presence of filters, as are commonly found in the venous sets, presents a major obstacle to effective cleaning prior to reuse. Likewise, arterial and venous sets tend to be long and cumbersome after they have been unwound, making it difficult to manipulate the set during reuse, storage, and setup.
Additionally, unlike dialyzers, certain components of the prior art blood lines are subjected to repeated mechanical force which, as they are made from materials which degrade with use, and thus are not ideal for reuse. This also raises safety issues. For example, the roller pump tubing segment typically carried by blood sets can quickly suffer from a deterioration in elasticity, since the pump segment tubing is crushed and reexpanded thousands of times by the action of the roller pump. The functioning of the pump segment tubing depends upon its elastic "spring back" capability. With a loss of some of that characteristic to spring back from the crushing provided by the roller pump, the amount of blood pumped per rotation of the roller pump rotor decreases. To make matters worse, this can go unnoticed as blood flow rates are typically calculated indirectly in the blood pump by a measurement of the rotational speed of the pump rotor, so that the flow rate may decrease even though the pump rotor speed is maintained. This can take place in part because plasticizers of the typically PVC roller pump segment may have leached out or otherwise because of characteristics of the materials used.
Also, a worn pump segment or diaphragm may shed into the pumped blood excessive amounts of particles from the plastic of which the segment is made.
Also, blood filters and transducer protector filters are reused only with difficulty and inefficiency, because the blood tends to clog the openings of the respective filters. Likewise injection sites may quickly wear out due to repeated punctures and the loss of elasticity as a consequence of use in a dialysis procedure. Organic material that collects in the puncture sites of elastomeric injection site partitions is especially difficult to remove and decontaminate.
Currently, arterial and venous sets for dialysis are reused in some clinics. However, in such reused sets the arterial blood line is generally not equipped with an arterial chamber, which prevents accurate monitoring of arterial pre-pump or post-pump pressures, raising a significant safety issue. Likewise, venous blood lines that are reused generally do not include a filter, which raises another significant safety issue. Furthermore, the reusable arterial and venous blood lines generally lack injection sites and other branch lines, which creates a significant inconvenience and a safety issue.
The reason for these deficiencies in the above reusable blood lines lies in the difficulty of reusing blood lines which have chambers, filters, injection sites, dead end side ports, and branch lines.
Luther et al. U.S. Pat. No. 4,612,170 discloses a blood oxygenator which has a removable and reusable heat exchanger. The remainder of the oxygenator and the blood lines are apparently not intended not to be reused.
Also, the Medisystems Corporation offered for sale during the 1970's and 1980's a neonatal venous line for dialysis in which a central chamber with filter was removably connected at both ends to lengths of tubing which each carried a branching connector site. The purpose of this was to permit replacement of the filter in case the filter became severely clotted during dialysis, to which neonatal dialysis is sometimes prone. It is not believed that any suggestion was made about reuse of any of the components of the neonatal venous line.